Many modem day aircraft, especially military aircraft, are equipped with wings having sections that are folded between a spread or deployed position where the aircraft is operational and a folded or stored position that allows the aircraft to be stored in a space efficient manor. Examples of such aircraft include missiles that have folding wing sections to allow storage in a launch canister and carrier based airplanes that must fold their wings for compact storage on and below the carrier deck.
Typically, the mechanisms that fold the wings must securely lock the wings in the deployed position for flying and, in the case of carrier based aircraft, must lock the wing in the stored position so that it does not accidentally deploy to the spread position due to wind and other forces on the carrier deck. The air load on the wing creates large moments on such mechanisms in both the deployed and stored positions. As modem aircraft move towards thinner wing sections, the space available to react the large moments is becoming increasingly restricted.
For carrier based aircraft, one traditional approach for the folding mechanism is to have a series of geared rotary actuators staged one after another in a line along the cord of the wing to form a "piano hinge" arrangement. The geared rotary actuators react all the wing loads and moments through their internal components. This tends to increase both the complexity and weight of the rotary actuators. Often, the systems also include a plurality of latch pins mounted in one of the wing sections that extend into mating bores on the other wing section to lock wing sections together in the deployed position. However, these devices can bind during engagement or disengagement due to the relatively snug fits required to ensure a secure lock of the wing sections in the deployed position. In addition to inhibiting reliable operation, this binding can produce undesirable wear in the devices. Other wing fold systems have been proposed utilizing linkage mechanisms. However, while these systems may be suitable for their intended purpose, there is always room for improvement.